In the history of headlines, “Liberals are smug” can be found in the same chapter of the obvious as “Lawyers complicate things” and “Graduate students hate you.”

Still, this week the source from which this particular nugget of wisdom was mined was not what you’d expect: It was Vox.

What is Vox? Memorably tagged “the young-adult site” by the Wall Street Journal’s James Taranto, it typically combines childlike oversimplification (for a while its mission was to reduce the most fraught issues to digital flashcards), high-school-student-government-nerd idealism, just-arrived-on-campus humorcidal earnestness and the millennial generation’s pretend fealty to big data.

All of these unite to produce a brand of progressive celebration that is to serious political analysis what Justin Bieber is to rock. Once Vox ran an “interview” with President Obama that was dolled up with so much propagandistic background music, frantic editing and fist-pumping editorializing that it amounted to the “Rocky IV” of wonkdom. “I’ve seen subtler Scientology recruitment films,” deadpanned Politico’s Jack Shafer.

Nevertheless, this week Vox launched a precision-guided missile of perspicacity that rose high into the air and scored a direct hit on its own deck.

“There is a smug style in American liberalism,” wrote Emmett Rensin. “It is a way of conducting politics, predicated on the belief that American life is not divided by moral difference or policy divergence — not really — but by the failure of half the country to know what’s good for them.”

It gets better: Writes Rensin, “Nothing is more confounding to the smug style than the fact that the average Republican is better educated and has a higher IQ than the average Democrat. That for every overpowered study finding superior liberal open-mindedness and intellect and knowledge, there is one to suggest that Republicans have the better of these qualities.”

Once Vox ran an “interview” with President Obama that was dolled up with so much propagandistic background music, frantic editing and fist-pumping editorializing that it amounted to the “Rocky IV” of wonkdom.

Ow. And: Whoa. For Vox, this was the equivalent of John Travolta plunging that hypodermic of adrenaline directly into Uma Thurman’s heart in “Pulp Fiction.” Vox Is Making Sense! It was the second-biggest shock of the week.

Rensin calls out posturing progressivism for its “condescending, defensive sneer toward any person or movement outside of its consensus, dressed up as a monopoly on reason.” He notes that the base of the Democratic Party morphed from working-class whites to an ungainly coalition of elite coastal professionals and minorities “largely excluded” from “decision-making.”

Rejected by their own core, the Democrats looked for excuses. It couldn’t be that their message was repellent to the masses. So they satisfied themselves with “the theory that conservatism, and particularly the kind embraced by those out there in the country, was not a political ideology at all. . . . Stupid hicks don’t know what’s good for them. They’re getting conned by right-wingers and tent revivalists until they believe all the lies that’ve made them so wrong. They don’t know any better. That’s why they’re voting against their own self-interest.”

That is a radical position (to progressives), albeit an obvious one (to everyone else), but Rensin goes a step further and attacks the pope of the One True Church of Smug Liberalism, Jon Stewart, for advancing “the idea that liberal orthodoxy was a kind of educated savvy and that its opponents were, before anything else, stupid.” (Note to younger readers: Stewart’s “The Daily Show” is a formerly popular comedy-current affairs show to which liberals used to turn for instruction in how to think about politics.)

It is moderately brave, if 30 years tardy, of Rensin to say that what he calls the “Correct Culture” (i.e., what everyone else has been calling political correctness since before he was born) has “come to replace politics itself.” When Rensin decries “a politics that insists it has no ideology at all, only facts,” it’s impossible not to think of President Obama, who, Rensin adds, this time only eight years tardily, embodied smugness when he offered no antidote for industrial job losses but instead dismissed disaffected working-class Americans as “bitter” folks who “cling to guns and religion.”

The Vox essayist concludes that progressives are afflicted by a “failure of empathy” (!) and should actually do something to help the working- and middle-class people whose interests they claim to represent, but if he went all the way down the same path, he would understand the core reason for liberal smugness: Ridiculing opponents is easier than arguing with them. Liberals don’t want debate, they want affirmation.